Endangered bird species: Report on whooping crane research and management--1974
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Strong site tenacity might prevent Palila (Loxioides bailleui), an endangered Hawaiian honeycreeper, from repopulating favorable habitats in their former range. We used radio telemetry during the nonbreeding and breeding seasons to study movements and dispersal rates of 57 Palila. All Palila remained in the study area, and home range sizes and movement distances were small relative to the potential mobility of the species. Banding and nesting studies revealed that Palila show strong site tenacity. An inverse correlation between movements and elevation was related to an elevational gradient in food supply. Translocations of Palila into presently unoccupied areas in their range might speed the recovery of this endangered species.
The Minnesota wolf (Canis lupus) population was estimated by the Minnesota Department of Natural Resources at 2,450 during winter 1997-1998 and had increased at an average annual rate of 4.5% since winter 1988-1989. The population may be removed from the federal endangered species list by 2002, and management would then return to the state. A federal recovery team recommended a population goal of 1,250
The Rallidae are a diverse group in their habitat selection, yet most North American species occur in or near wetlands As a consequence, most species are subject to habitat enhancement or perturbation from waterfowl management programs. The overall effects of these management programs relative to rallid conservation have been assessed for few species, and there is a need for synthesis of such information. In the cases of some species or raves, population status is not known, and suggested directions for conservation and management are needed. Rare, endangered, or status undetermined species or races often occur in areas where related species are classified as game birds, and the effects of such hunting on rarer forms are not known. Their generally secretive nature, the endangered status of several races and populations, and continued loss of habitat and threats to present habitat, warrant an examination of the conservation status of the North American taxa in this group. In 1977, a committee of the International Association of Fish and Wildlife Agencies summarized available information on management and biology of American Coots ( Fulica americana ), rails, and gallinules in North America (Holliman 1977). That summary was intended to provide relatively complete information on conservation of these species, and also to provide guidance for research within the U.S. Fish and Wildlife Service's (FWS) Accelerated Research Program for Webless Migratory Shore and Upland Game Birds (ARP). Subsequently, a number of rallid studies were funded under this program. The program was eliminated in 1982, following substantial research activities on North American rallids. Since the demise of the ARP, additional research on rallids in North America has focused on an area the International Association of Fish and Wildlife Agencies report failed to cover in detail--that of endangered rallids in the U.S. and their possessions. Most of these studies have been of threatened and endangered taxa in western coastal marshes. This report updates and summarizes information on North American rallids since the ARP report and identifies the major conservation problems of this group with the intent of focusing future efforts on these priority issues. Consideration of island forms occurring within U.S. possessions is beyond the scope of this report, mainly because of the special conservation problems associated with their insular distribution. The major topics include habitat requirements, effects of habitat and hunting management techniques currently practiced on wetland areas, and conservation of endangered and threatened populations. Research needs are identified. Habitats of the American Coot are similar to those of several waterfowl species, and the biology of coots is considered only as it is typical of rails in general.
In the Pacific Northwest, fish communities are found in a diverse array of aquatic habitats ranging from the large coastal rivers of the temperate rainforests, to the fragmented and sometimes ephemeral streams of the xeric interior basins, and high-elevation streams and lakes in the mountainous areas (Rieman et al. 2003). Only high-elevation lakes and streams isolated above barriers to fish passage remained historically devoid of fish because they were never invaded following Pleistocene glaciation (Smith 1981). Despite this widespread distribution and once great population abundances, taxonomic diversity of fishes in these forested systems is naturally lower than in aquatic habitats in the eastern U.S. (Reeves, Bisson, and Dambacher 1998). Interactions among factors that influence species richness in aquatic systems (e.g., basin size, long-term stability of habitat, and barriers to colonization; Smith 1981) continue to influence the occurrence and persistence of fishes in these systems today. Consequently, the larger low-elevation rivers and estuaries support the greatest variety of fish species. In the high-elevation tributary streams, fish communities are less complex because these aquatic systems were less climatically and geologically stable, and fish populations were smaller and more prone to local extirpation. Furthermore, barriers to fish passage inhibited dispersal and colonization (Smith 1981). Streams in forested landscapes generally support salmon and trout, Oncorhynchus spp., whitefish Prosopium spp., sculpins Cottus spp., suckers Catostomus spp., and minnows (Cyprinidae), but in some of the colder streams, chars (e.g., Salvelinus confluentus and Salvelinus malma ) and lampreys (Petromyzontidae)may also occur (Rieman et al. 2003). Although biodiversity defined in terms of fish species richness is low in the Pacific Northwest, intraspecific variability is high, and polytypic fish species are common in the diverse aquatic habitats of the region. For example, the salmonids in the coastal rivers and streams, and the larger interconnected streams, rivers, and lakes of the interior exhibit a variety of ecotypes and migratory life histories (Healey 1986; Trotter 1989; Larson and McIntire 1993; Northcote 1997). This life-history variation appears to be associated with adaptation to spatial and temporal variation in environment (e.g., Schaffer and Elson 1975; Carl and Healey 1984; Beacham and Murray 1987), and there is some evidence of the genetic heritability of life-history traits (Carl and Healey 1984; Gharrett and Smoker 1993; Hankin, Nicholas, and Downey 1993). Persistence of any level of biological organization (e.g., life-history type, population, metapopulation, subspecies, species, community) is related to the interaction of environmental and biological components, and intraspecific diversity is a means of spreading risk ( sensu den Boer 1968) of extirpation in dynamic environments (Gresswell 1999). Unfortunately, despite the broad distribution and extensive intraspecific diversity, persistence of native fishes is uncertain in the Pacific Northwest. Many populations of anadromous salmonids, once synonymous with vigorous biological communities throughout the region, are threatened with extinction (Nehlsen, Williams, and Lichatowich 1991; Frissell 1993; Thurow, Lee, and Rieman 1997). Furthermore, over half of the native taxa in the Columbia River Basin are either listed under the Endangered Species Act, are being considered for listing, or are deemed sensitive by the management agencies (Lee et al. 1997; Thurow, Lee, and Rieman 1997). Potamodromous species like bull trout Salvelinus confluentus are estimated to occur as strong populations in less than 5% of their potential range (Rieman, Lee, and Thurow 1997). Although not currently listed under the endangered species list, the coastal cutthroat trout Oncorhynchus clarki is managed as a sensitive species in Oregon and California (Hall, Bisson, and Gresswell 1997). Native non-game fishes have rarely been monitored, but populations of species such as large-scale suckers ( Catostomus macrocheilus ), squawfish ( Ptychocheilus umpquae ), and Pacific lamprey ( Lampetra tridentata ) also are declining in some drainages (Oregon Department of Fish and Wildlife, unpublished data).
The Prairie du Chien dredge material site contains about 100,000 cubic meters of material dredged from the East Channel of the Mississippi Riverin1976. Previous studies in that area suggested a rich molluscan fauna, but most studies were only qualitative or simply observations. Our study of this material was designed to determine the density and diversity of molluscan fauna, to assess changes in the fauna, to identify endemic species previously unreported, and to evaluate the status of the endangered Lampsilis higginsi. Ten cubic meters of dredge material were sieved to recover shells. Molluscan fauna at the site contained38 species of naiades and up to 1,737 identifiable valves per cubic meter. The endangered L. higginsi ranked18th In occurrence, accounted for only 0.52% of the identifiable shells, and averaged about three valves per cubic meter. From a total of 813 kg of naiades and gastropods, 6,339 naiad valves were identified. Five naiad species were collected at the site for the first time, and Eploblasma triquetra had not been reported previously in the Prairie du Chien area. Although the molluscan fauna has changed, the East Channel at Prairie du Chien is obviously suitable for L. higginsi.
We describe the fifth verified nest and first verified egg of the Akiapolaau (Hemignathus munroi), an endangered Hawaiian honeycreeper. We dispute the validity of Bryan?s (1905a) description of three eggs and two nests of the Akiapolaau. Eggs that he attributed to this species were much smaller than ours, and his nest descriptions did not match the only nest apparently belonging to the Akiapolaau in the B. P. Bishop Museum in Honolulu, where Bryan worked. Twigs and bark were distinctively combined in the nest that we examined. We compare eggs and nests of the Akiapolaau with those of other Hawaiian honeycreepers.
Mercury concentrations in the sediments of south Florida wetlands have increased three fold in the last century (Rood et al. 1993). Because south Florida is home to many endemic and endangered species, it is important to understand the potential impacts of mercury in this ecosystem's food web. Recent research by Malley et al. (1996) has shown mollusks to be sensitive indicators of methyl mercury which can reflect small differences in background methyl mercury concentrations. In this study, we attempted to determine if the apple snail (Pomacea paludosa) or its eggs are good indicators of bioavailable mercury. Then, using the apple snail as an indicator, we attempted to determine geographic differences in the concentrations of mercury in south Florida.
Most of the 27 species and subspecies of surviving crocodilians have declining populations and 22 of them are considered to be severely endangered (IUCN 1971). The United States population of the American Crocodile is no exception; it probably numbers between I00 and 300 individuals (OGDEN 1976). Nests of the species have been regularly surveyed by the staff of Everglades National Park. Our sample consists of eggs that remained in nests after the hatching of broods and of one clutch laid in captivity by an unmated female. Analysis of these samples for organochlorine contaminants has permitted a detailed examination of their contaminant loads and has allowed comparisons with a small sample analyzed in 1972 (OGDEN et al. 1973).
The grizzly bear ( Ursus arctos horriblilis ) in the lower United States was declared threatened in 1975 under the Endangered Species Act of 1973 (16 U.S.C. 15-31-1544). According to that Act, the U.S. Fish and Wildlife Service had to prepare a plan to recover populations to levels where the species could be conserved and delisted from its threatened status. The Recovery Plan (U.S. Fish and Wildlife Service 1993) uses counts of distinct females with cubs-of-the-year as a recovery parameter in several grizzly bear ecosystems. The total number of these females is assumed to be the minimum number with cubs born in the current year. To our knowledge, this technique, its methodology, and value as a population indicator have never been adequately explained or discussed. Thus, we describe the methodology and assess its potential for continued use in the Yellowstone ecosystem.
The recovery strategy for an endangered species requires accurate knowledge of its distribution and geographic range. Although the best available information is used when developing a recovery plan, uncertainty often remains in regard to a species actual geographic extent. The arroyo toad ( Anaxyrus californicus ) occurs almost exclusively in coastal drainages, from Monterey County, California, south into northwestern Baja California, Mexico. Through field reconnaissance and the study of preserved museum specimens we determined that the four reported populations of the arroyo toad from the Sonoran Desert region of Riverside, San Diego, and Imperial counties, California are in error. Two additional sites in the Sonoran Desert are discussed regarding the possibility that the arroyo toad occurs there. We recommend the continued scrutiny of arroyo toad records to maintain a high level of accuracy of its distribution and geographic extent.
Predation can be a factor in preventing prey population growth and sustainability when prey populations are small and fragmented, and when predator density is unrelated to the density of the single prey species. We conducted monthly raptor surveys from February 2007 to May 2009 in adjacent areas of the Texas Southern High Plains (USA) that do and do not support lesser prairie-chickens ( Tympanuchus pallidicinctus ), a candidate for protection under the Endangered Species Act. During the summer period corresponding to prairie-chicken nesting and brood-rearing, Swainson's hawks ( Buteo swainsoni ) were the most abundant raptor. During the lekking and overwintering period, the raptor community was diverse, with northern harriers ( Circus cyaneus ) being the most abundant species. Raptor abundance peaked during the early autumn and was lowest during the spring. Utility poles were a significant predictor of raptor density at survey points and Swainson's hawks and all raptors, pooled, were found in greater densities in non-prairie-chicken habitat dominated by mesquite ( Prosopis glandulosa ). Avian predation risk on prairie-chickens, based on presence and abundance of raptors, appears to be greatest during winter when there is a more abundant and diverse raptor community, and in areas with utility poles.
Glochidia of the endangered unionid mussel Lampsilis higginsi (Lea) are morphologically similar to those of several other species in the upper Mississippi River. Life history details, such as the timing of reproduction and identity of host fish, can be readily studied if the glochidia of L. higginsi can be distinguished from those of related species. Authors used light and scanning electron microscopy and statistical analyses of three shell measurements, shell length, shell height, and hinge length, to compare the glochidia of L. higginsi with those of L. radiata siliquoidea (Barnes), L. ventricosa (Barnes), and Ligumia recta (Lamarck). Glochidia of L. higginsi were differentiated by scanning electron microscopy on the basis of a combined examination of the position of the hinge ligament and the width of dorsal ridges, but were indistinguishable by light microscope examination or by statistical analyses of measurements.
The Poouli (Melamprosops phaeosoma) is an endangered Hawaiian honeycreeper found only on Maui, Hawaii. It was rare at the time of its discovery in 1973, but by 1997 was on the brink of extinction with fewer than six individuals left. Two specimens were collected for the description of the species, but both proved to be immature by comparison with a pair of adults at a nest. Until 1997 no Poouli had ever been captured alive, and consequently descriptions of adult Poouli were produced from field observations. In 1997, I captured an adult male Poouli which is described here for the first time. Detailed comparisons of the plumage of this adult with that of an immature specimen and previous descriptions of the species are discussed in this paper, as are differences in plumage between adult and immature males and females that may aid the sexing and ageing of birds in the field.
The United States Fish and Wildlife Service has determined that the black-tailed prairie dog (Cynomys ludovicianus) warrants listing as a threatened species under the Endangered Species Act. Central to any conservation planning for the black-tailed prairie dog is an appropriate detection and monitoring technique. Because coarse-resolution satellite imagery is not adequate to detect black-tailed prairie dog colonies, we examined the usefulness of recently available high-resolution (1-m) satellite imagery. In 6 purchased scenes of national grasslands, we were easily able to visually detect small and large colonies without using image-processing algorithms. The Ikonos (Space Imaging(tm)) satellite imagery was as adequate as large-scale aerial photography to delineate colonies. Based on the high quality of imagery, we discuss a possible monitoring program for black-tailed prairie dog colonies throughout the Great Plains, using the species' distribution in North Dakota as an example. Monitoring plots could be established and imagery acquired periodically to track the expansion and contraction of colonies.
Greater sage-grouse ( Centrocercus urophasianus ; sage-grouse) are highly susceptible to infection with West Nile virus (WNV), with substantial mortality reported in wild populations and in experimentally infected birds. Although sage-grouse are hunted throughout much of their range, they have also recently been considered for protection under the Endangered Species Act. We used blood samples collected on filter-paper strips during the 2006–2010 Oregon, USA, annual sage-grouse hunt to survey for specific WNV-neutralizing antibodies that indicate a previous infection with WNV. During this period, hunters submitted 1,880 blood samples from sage-grouse they harvested. Samples obtained were proportional for all 12 Oregon sage-grouse hunting units. Laboratory testing of 1,839 samples by the WNV epitope-blocking enzyme-linked immunosorbent assay (bELISA) followed by plaque reduction neutralization test on bELISA-positive samples yielded 19 (1%) and 1 (0.05%) positive samples, respectively. These data provided early baseline information for future comparisons regarding the prevalence of WNV-specific neutralizing antibodies in sage-grouse in Oregon. This methodology may provide other states where sage-grouse (or other species) populations are hunted and where WNV constitutes a species conservation concern with a viable option to track the relative prevalence of the virus in populations.
California Clapper Rails ( Rallus longirostris obsoletus ) are an endangered waterbird that forage in tidal-marsh habitats that pose risks from mercury exposure. We analyzed total mercury (Hg) in six macro-invertebrate and one fish species representing Clapper Rail diets from four tidal-marshes in San Francisco Bay, California. Mercury concentrations among individual taxa ranged from lowest at Colma Creek (mean range: 0.09–0.2 μg/g dw) to highest at Cogswell (0.2–0.7), Laumeister (0.2–0.9) and Arrowhead Marshes (0.3–1.9). These spatial patterns for Hg matched patterns reported previously in Clapper Rail blood from the same four marshes. Over 25% of eastern mudsnails ( Ilyanassa obsolete ) and staghorn sculpin ( Leptocottus armatus ) exceeded dietary Hg concentrations (ww) often associated with avian reproductive impairment. Our results indicate that Hg concentrations vary considerably among tidal-marshes and diet taxa, and Hg concentrations of prey may provide an appropriate proxy for relative exposure risk for Clapper Rails.
We studied the breeding ecology of the critically endangered Puaiohi ( Myadestes palmeri ), a poorly known Hawaiian thrush endemic to the island of Kauai. From 1996 through 1998, we monitored 96 active nests over the course of three breeding seasons. Mean clutch size was 2.0, and pairs produced an average of 1.5 fledglings/successful nest. Pairs renested after failure and some raised multiple broods. The mean annual reproductive effort was 2.1 nesting attempts/territory, and pairs produced a mean 1.1 fledglings/attempt. Large differences in nesting effort and productivity occurred among years, with mean number of fledglings/territory ranging from 0.4 to 4.9. Predation by owls (probably Short-eared Owls, Asio flammeus ) and introduced rats (probably black rats, Rattus rattus ) accounted for most nest failures. The presence of non-breeding floaters in the population and their largely unsuccessful attempts to gain territories in the study area suggest that the population is near carrying capacity. The high reproductive potential of the Puaiohi may help explain its persistence despite the species' historical rarity.